This invention relates to anti-theft devices for tandem wheel vehicles, primarily dual axle trailers. More particularly, it relates to a device which will secure each end of a bar to the wheels of a tandem axle trailer. The invention prevents removal of the bar from the wheels without a key. When the wheels are linked together with this bar, the movement of one wheel will transfer torque to the second wheel. In this fashion, the wheels of the trailer are prevented from rotating and so prevent theft of the trailer.